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chemistry wjec > Crude Oil, Fuels, and Organic Chemistry > Flashcards

Crude Oil, Fuels, and Organic Chemistry Flashcards

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1
Q

What is organic chemistry

A

The chemistry of carbon-based compounds

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2
Q

What do plastics use as a raw material

A

Crude oil

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3
Q

What is crude oil made of

A

Hydrocarbons

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4
Q

What is the method for separating out different types of crude oil

A

Frational distillation

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5
Q

Describe fractional distillation

A
  • The oil is heated causing it to boil and turn into a gaseous mixture
  • As the oil cools, the chemicals with lower boiling points will be the first to condense
  • At various points the condensing liquid is extracted from the column
  • The larger the molecule is, the lower its boiling point will be
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6
Q

How pure are the fractions from fractional distillation

A

Not at all - they’re a mixture of alkanes with broadly similar boiling points

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7
Q

Why do larger hydrocarbons have lower boiling points?

A

Because it takes a lot more energy to break all of the separate bonds

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8
Q

What is the second effect of long hydrocarbons

A

They’re more viscous (thick)

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9
Q

Give some examples of uses of hydrocarbons

A

Petrol, diesel, paraffin, methane, lubricating oi

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10
Q

What has to happen to a fuel for it to burn

A

It has to vaporise, as it is the vapour that burns, and to do this it is useful to have a low viscocity

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11
Q

What is a combustion reaction

A

A chemical reaction where a substance reacts with oxygen to produce heat, light, and new products

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12
Q

Which substances can be used as fuel

A

Any substance which is combustible

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13
Q

What happens in combustion when not enough oxygen is around

A

Incomplete combustion, where carbon is formed, as well as carbon monoxide, carbon dioxide, and water

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14
Q

Why is it important to avoid incomplete combustion

A

Because it creates carbon monoxide, which is toxic and we cannot detect

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15
Q

What is the issue with burning sulfur

A

Acid rain

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16
Q

How do we calculate the energy released with fuels

A

Energy transferred (J) = mass of water heated (g) x 4.2 x temperature rise

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17
Q

Why are we interested in hydrogen as a fuel?

A

Because it only creates water when it burns

2H(2) + O(2) = 2H(2)O

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18
Q

What are the problems with using hydrogen fuel cells in cars

A
  • It’s very flammable and can explode
  • For storage it must be chilled, compressed, and kept in strong tanks (-250)
  • Manufacturing hydrogen requires the burning of CO(2)
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19
Q

Why is hydrogen used as a rocket fuel

A

Because it’s light and very powerful, burning at over 3000 degrees

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20
Q

How can we remove oxygen, heat, and fuel from the fire triangle

A

Oxygen - fire blankets, closing doors, covering a pan with a wet towel (carbon dioxide sinks oxygen rises)
Heat - putting water on a fire
Removing fuel - prevention. making clothing flame resistant and managing forests

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21
Q

How can we make the larger fractions from fractional distillation more useful

A

By catalytic cracking

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22
Q

How does catalytic cracking work

A

Vapour containing the unwanted fractions is passed over a very hot catalyst surface and this breaks them up

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23
Q

Give an example of catalytic cracking

A

C(15) H(32) = 2C(2)H(4) + C(8)H(18)

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24
Q

What types of hydrocarbons are created by catalytic cracking

A

A mixture of alkenes and alkanes

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25
Q

What types of hydrocarbons are alkanes

A

Saturated ones

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26
Q

Which types of alkanes do we have to know

A 
Methane CH(4)
Ethane C(2)H(6)
Propane C(3)H(8)
Butane C(4)H(10)
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27
Q

What type of compounds are alkanes

A

Homologous ones (very similar)

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28
Q

What are alkenes

A

Unsaturated hydrocarbons with a double bond between two carbon atoms

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29
Q

What is the name of a reaction where another atom is added to an alkene

A

An addition reaction

30
Q

What is the name for when hydrogen is added to an alkene

A

Hydrogenation

31
Q

How is hydrogenation achieved

A

By heating the alkene under pressure in the presence of a metallic catalyst

32
Q

What is the chemical test for alkenes

A

That they turn orange bromine water colourless

33
Q

How do you name a complex alkane/alkene

A
  • Find the longest chain of carbon atoms (not always a straight line). This will be the “first name”
  • Add ane or ene
  • Work out how to number the carbon atoms. Carbon no.1 should be at the end nearest to a substituent group
  • The substituent groups should be named according to how many carbon atoms they have
  • In front of the name goes a prefix to show how many group there are
34
Q

Define isomers

A

Two compounds that have the same formular but a different structural formula

35
Q

Define polymer

A

A substance which has a molecular structure built up chiefly or completely from a large number of similar units bonded together

36
Q

Give an example of a plastic hydrocarbons can make

A

Polythene, polypropene, or PVC

37
Q

What are the two types of plastics

A

Thermoplastics - soften when heated

Thermosets - resistant to heat

38
Q

What are thermosets used for

A

Light fittings and pan handles

39
Q

What are thermoplastics used in

A

Household containers

40
Q

What are thermoplastics made of

A

Polymer chains that aren’t linked together so can slide on one and other

41
Q

How are thermosets constructed

A

The polymer chains have strong cross linkages which hold the structure together

42
Q

How are thermoset plastics made

A

In liquid form - once set they can’t be remelted

43
Q

What are the molecules (such as ethene) used to construct polymers called

A

Monomers

44
Q

What are the two types of polymers

A
  • Addition polymers (made from only one type of monomer)

- Condensation polymers (two or more types of monomer)

45
Q

How is polythene made

A

By joining ethene molecules, heating them under pressure

46
Q

How many ethene molecules join together making polythene

A

Between 2000 and 20000

47
Q

What is polythene used in

A

Carrier bags

48
Q

What is polypropene used in

A

Dishwasher safe food containers and piping

49
Q

What is PVC used in

A

Electrical insulation, clothing, pipes

50
Q

What is PTFE used in

A

Non stick coating for cookware and irons

51
Q

What is the general formula for alcohols

A

C(n)H(2n+1)OH

52
Q

How are alcohols named

A

Like alkanes but with -ol at the end

53
Q

Which alcohols do you have to know

A 
Methanol
Ethanol
Propan - 1 - ol
Propan - 2 - ol
Butanol
54
Q

What happens in alcohol isomers

A

The OH molecule is positioned differently

55
Q

What type of alcohol is in alcoholic drinks

A

Ethanol

56
Q

How does fermentation happen

A

Yeast produces ethanol from sugar (only in anearobic conditions)

57
Q

What is the formula for fermentation

A

C(6)H(12)O(6) = 2CO(2) + 2C(2)H(5)OH

58
Q

What is the fermentation reaction catalyzed by

A

Enzymes which are produced by the yeast

59
Q

What conditions are needed for fermentation

A
  • The temperature should be between 25 and 50 degrees
  • The fermentation tank has to be kept sterile
  • Oxygen must be kept out
  • Carbon dioxide has to be able to escape or else pressure will build up
60
Q

What is the use of bioethanol

A

As a fuel - usually ethanol is mixed with petrol

61
Q

What are the positives of ethanol as a fuel

A
  • It’s renewable
  • It emits less carbon dioxide than petrol
  • It produces less soot and carbon monoxide
62
Q

What are the disadvantages of ethanol as a fuel

A
  • Fossil fuels are used in the production of bioethanol
  • Ethanol is less efficient than petrol
  • Engines need modifications to process ethanol
  • Lots of farmland is needed to produce ethanol
63
Q

How is vinegar made

A

Using ethanol - ethanoic acid is found in vinegar

64
Q

What family of acids does ethanoic acid come from

A

Carboxylic acids, containing the group -COOH

65
Q

What kind of reaction is converting ethanol to ethanoic acid

A

An oxidation reaction caused by microorganisms in aerobic conditions

66
Q

How can alcohols be detected

A

By reaction with potassium dichromate and sulfuric acid, which will turn green if alcohol is present

67
Q

What bond do alcohols have

A

An -OH one

68
Q

What bond do carboxylic acids have

A

Bonds between carbon and oxygen, and between oxygen and hydrogen (-COOH)

69
Q

What technique can scientists use to see what bonds are in a substance

A

Infrared spectroscopy

70
Q

How does infrared spectroscopy work

A

Substances are but in an infrared spectrometer and infrared light is shone through them - different chemical bonds absorb different wavelengths of light, which can be displayed as an infrared spectrum. The peaks and troughs of this identify certain bonds, so this pattern (fingerprint) is unique to a particular molecule

chemistry wjec (8 decks)

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